R. Bruce Wallace III, MD, FACS
With the aging of baby boomers in the US as well as in most other industrialized nations, multifocal and accommodating IOLs are sure to gain popularity. The Array lens (Advanced Medical Optics, Inc., Santa Ana, CA) is the first multifocal IOL to receive FDA approval. With proper patient selection, accurate biometry, and astigmatism control, my colleagues and I have achieved excellent visual outcomes with this refractive multifocal lens.DESIGN
The Array is a distance-dominant, refractive multifocal lens. The central portion of the optic provides most of the distance vision. The first near ring begins at the 2.1-mm optical zone diameter of the optic, and three additional rings alternate between distance and near focus (Figure 1). These multifocal zones have been recently redesigned and named Rezoom (see “The Rezoom Lens” on p. 94). The FDA recently granted the Array an expanded power range of -10.00 to +30.00D.
A number of published studies demonstrate the value of the Array multifocal lens compared to monofocal controls.1-3 After years of experience with the Array lens, my colleagues and I have found that roughly 80% of bilaterally implanted patients use glasses less than 20% of the day.
Nevertheless, I am surprised by the infrequent use of the Array by ophthalmologists. Many factors have contributed to confusion about this IOL. Early on, patients confronted surgeons with unwanted visual images after Array implantation. Rings or halos around lights at night commonly occurred, resulting in occasional IOL exchange. Later, I realized that visual cortical adaptation allowed many patients to learn to ignore the halos, especially after implantation of the Array lens in their second eye. My colleagues and I also found, however, that some patients required more chair time, both pre- and postoperatively, a circumstance that raised concerns over less efficient patient care in this new reality of lowered cataract surgery reimbursement. In spite of these drawbacks, Array patients enjoy dependable near acuity in all fields of gaze (unlike with bifocals) with physiologic stereoacuity (not seen with monovision).
Additionally, we found that, by stressing the unique features of the Array lens, patients tended to ignore the importance of biometry and astigmatism control, as well as treatment for problem dry eye and posterior capsular opacification (PCO) postoperatively. Kevin Waltz, MD, of Indianapolis, Indiana, and I decided it would be best to give this procedure a name, which would help to de-emphasize the IOL and stress the fact that this procedure includes the use of a special lens. Dr. Waltz came up with the name PRELEX, an acronym for presbyopic lens exchange. Just as LASIK had become a commonly understood, we felt that PRELEX would similarly allow more patients to appreciate that there are procedures like this available to correct the problems associated with presbyopia.By far, the majority of the individuals in whom we implant the Array lens are cataract patients. To our precataract patients, we explain that PRELEX is an off-label use of an FDA-approved procedure.
PATIENT SELECTION AND COUNSELING
The best candidates for the Array lens are unhappy hyperopic presbyopes. Coincidentally, these patients are generally suboptimal LASIK candidates. We look for patients whose eyes have clinically significant lenticular changes and who accept the possible need for glasses after surgery. The best candidates are agreeable, understanding, open-minded, and forgiving. We explain that the Array lens gives a person more visional function without the use of glasses and that there is no significant loss of BSCVA in our experience. We emphasize to patients that they will need to adjust to a new visual system and that they will see a glow around lights at night that may be bothersome at first but will become less noticeable with time. We look for patients who have good tear function, whose pupils are of adequate size, and who are easy to refract. Outcomes improve when biometry is within normal expectations with reliable axial lengths and Ks that match their refractive cylinder.THE SURGICAL PROCEDURE
Preoperative medications include the use of tropicamide instead of cyclopentolate. We like to see the pupil become physiologic soon after surgery. Under topical anesthesia, we use low-energy, controlled phacoemulsification with the Sovereign system with Whitestar Technology (Advanced Medical Optics, Inc.) and perform limbal relaxing incisions to address astigmatism.POSTOPERATIVE CARE
Visual confusion is common in patients who receive the Array lens in only one eye, and they may need to wear readers during the first few weeks after surgery. We remind patients that halos are expected and will become less noticeable with time. We have found that a big inhibitor of sharp distance and near vision postoperatively is an inadequate tear film, with PCO being a close second. Because the lens divides light rays for distance, intermediate, and near vision, it is natural that a poor tear film and/or PCO would affect multifocal patients more than monofocal patients.Obviously, residual cylindrical and spherical error can also interfere with quality of vision and may require surgical correction.
The future of multifocal lenses and alternatives such as accommodating IOLs, is bright. I encourage surgeons who are not yet ready to implant these lenses to take advantage of the lens surgery of today with monofocal IOLs and perform outcomes analysis and astigmatic correction so they will be able to achieve good results when they decide to use these newer IOLs. I expect at least a portion of most cataract surgeons' IOLs will be multifocal and/or accommodative in the next 2 to 3 years. The Array has gotten us off to a good start.
R. Bruce Wallace III, MD, FACS, is Medical Director of Wallace Eye Surgery in Alexandria, Louisiana Dr. Wallace serves as Clinical Professor of Ophthalmology at the LSU School of Medicine and Assistant Clinical Professor of Ophthalmology at Tulane School of Medicine, both in New Orleans. He consults for Advanced Medical Optics, Inc., but states that he holds no financial interest in any product mentioned herein. Dr. Wallace may be reached at (318) 448-4488; email@example.com. Sen N, Sarikkola A, Uusitalo R, Laatikainen L. Quality of vision after AMO Array multifocal intraocular lens implantation. J Cataract Refract Surg. 2004;30:2483-2493.
2. Javitt J, Wang F, Trentacost D, et al. Outcomes of cataract extraction with multifocal intraocular lens implantation. Ophthalmology. 1997;104:589-599.
3. Leyland M, Zinicola E. Multifocal versus monofocal intraocular lenses in cataract surgery. Ophthalmology. 2003;110:1789-1798.
W. Andrew Maxwell, MD, PhD
Patients' desire for a quality range of vision and freedom from spectacles has prompted the development of a new technologically advanced IOL. The Acrysof Restor IOL (Alcon Laboratories, Inc., Fort Worth, TX) effectively addresses this desire through an apodized diffractive optic technology. Diffraction is a familiar term in ophthalmology that describes the bending of light as it comes in contact with a step. This topic has been frequently discussed, because it applies to various ophthalmic lenses and optical equipment. What is familiar to optical physicists but may be new to the ophthalmic surgeon is apodization. This principle is commonly used in microscopy and astronomy as the radial treatment of a lens system to manage light and optimize image quality. Alcon researchers have applied this principle to the Acrysof Restor IOL by gradually decreasing the step heights of its 3.6-mm diffractive area from 1.3µm centrally to 0.2µm peripherally. This application of apodization harmonizes the distribution of light energy between two primary focal points based on the activity and light conditions to which the patient is subjected. The benefit for a patient is a quality range of vision independent of pupil size with minimal visual disturbances as compared with older technologies. An added benefit is that this advanced apodized diffractive technology is also integrated into the Acrysof single-piece platform, known for stability and biocompatibility within the eye.MEETING EXPECTATIONS
As advanced as the optics of the Restor IOL are, the successful implementation of this lens involves managing the traditional pre- and postoperative challenges of ophthalmic surgery. Challenges found with cataract surgery may be divided into two main categories of complications. The first involves general cataract complications and includes corneal edema, endothelial cell loss, and cystoid macular edema. The second complication, and arguably the more difficult of the two, is patients' unmet visual expectations, including a loss of acuity, glare, halos, or other visual disturbances. Avoiding these complications begins with surgeons' choosing not only an appropriate optic design but also paying close attention to patient selection and surgical technique.PATIENT SELECTION
Key quality-of-life endpoints from the US clinical trials indicated that subjects implanted with the Acrysof Restor IOL were highly satisfied, experienced minimal visual symptoms and few social limitations, and were generally free from spectacles (Figure 2). These results, when coupled with the visual acuity outcomes, strongly suggest that subjects implanted with the investigational Acrysof Restor IOL experienced a quality range of vision with positive lifestyle benefits. However, as with any IOL modality, effective patient selection and biometric calculations were an essential component to reaching these successful outcomes. Appropriate candidates for the Acrysof Restor IOL want to be free of spectacles and have less than 1.00D of postoperative astigmatism. European experience with the Restor IOL has revealed that optimal patient satisfaction is obtained with binocular implantation that targets emmetropia or slight hypermetropia. Biometric methodology and formula selection have also been essential for success.The SURGICAL TECHNIQUE
Surgical technique for implanting the Acrysof Restor IOL is the same as that used with other Acrysof single-piece models. However, it is important to pay attention to detail in order to perform not only a successful but also an exceptional procedure. For example, the incision should be located and contructed in such a manner as to minimize or reduce postoperative astigmatism. Additionally, care should be taken to make a capsulorhexis that will completely cover the implanted optic's edge. Also, surgeons should be conscious of any residual viscoelastic behind the lens and remove it before softly seat the lens on the posterior capsule. These steps will aid in providing predicted refractive outcomes and long-term stability.CONCLUSION
The apodized diffractive optic of the Acrysof Restor IOL represents a new innovation in IOL technology. The lens has effectively led to superior visual performance and patient satisfaction as evidenced by its associated clinical trials. However, as with any IOL technology, a surgeon must take the challenge to preoperatively select appropriate candidates, instill proper expectations, and then meet those expectations with optimal biometric methodologies and surgical technique.
W. Andrew Maxwell, MD, PhD, is in private practice at California Eye Institute in Fresno. He is a consultant to Alcon Laboratories, Inc., but states that hedoes not hold a financial interest in any product mentioned herein. Dr. Maxwell may be reached at (559) 449-5010; firstname.lastname@example.org.Crystalens Experience After the FDA Trial
Steven J. Dell, MD
Although the Crystalens (Eyeonics, Inc., Aliso Viejo, CA) has received FDA approval for cataract surgery in adults, it is increasingly being used offlabel for refractive lens exchange. Its off-label use is particularly appropriate for patients 50 to 60 years old seeking refractive surgery. Refractive lens exchange offers distinct advantages compared with keratorefractive procedures in these patients, because they often have early lenticular changes that will continue to influence their refractive error in the future. Many of these patients also have dry eye issues that may be aggravated by LASIK. The opportunity to correct ametropia as well as provide accommodation makes the Crystalens an attractive alternative for these patients.EFFECTIVENESS
With any new technology, surgeons' and patients' concerns about long-term efficacy are appropriate. Three-year data from the Crystalens' FDA trial are now available. In short, they demonstrate the preservation of the accommodative effects of the lens with a slight improvement beyond the 1-year data.1 Although all patients could see at least J3 bilaterally through the distance correction at both 1 and 3 years postoperatively, the percentage achieving J1 or better increased from 50% at 1 year to 68% at 3 years (Figure 3). Bilateral uncorrected distance acuity remained excellent at the 3-year mark, with 97% achieving 20/25 or better.COMPLICATIONS AVOIDANCE AND
Thousands of implantations occurring since the FDA approval have provided valuable insights. Notably, a watertight wound closure is extremely important with the Crystalens. As a result of the lens' unique hinged architecture, wound leaks in the early postoperative period can allow the lens to shift anteriorly, resulting in unexpected myopia. Similarly, incomplete cortical removal can lead to aggressive capsular contraction, which can distort the highly flexible Crystalens and result in its tilting. The remedy for this condition is a YAG posterior capulotomy, which will release the tension causing the lens to tilt. An extremely small capsulorhexis is also a risk factor for aggressive capsular contraction, perhaps due to a larger number of residual anterior lens epithelial cells. An overly large capsulorhexis is not advisable, because it can allow forward movement of the Crystalens prior to its stable fixation within the capsular bag. I typically suggest a 5-mm capsulorhexis for this lens.NEW FINDINGS
Another interesting development is the identification of an additional proposed mechanism of action for the lens. Some surgeons have voiced concerns that the objective demonstration of forward movement of accommodating IOLs cannot fully explain the near acuities achieved by some patients, particularly with low-powered IOLs.2 These IOLs would need to move more compared with a high-powered IOL to achieve a given level of accommodation. In a study of a small group of FDA trial participants that used immersion ultrasound with pharmacological manipulation of accommodation, the Crystalens moved an average of 0.84mm anteriorly.1 This level of movement, when combined with the pseudoaccommodative effects common to all IOLs, can explain the near vision abilities of many of these patients, but some Crystalens patients seem to see better at near than would be expected of their IOL powers. An examination of Tracey (Tracey Technologies, Inc., Bellaire, TX) wavefront maps comparing near and distant fixation on a coaxial target has revealed the induction of myopic astigmatism with near gaze in Crystalens patients3 (Figure 4). This induced astigmatism could be consistent with a very slight flexing of the optic with near gaze. Similar Tracey wavefront patterns of induced myopic astigmatism are seen in phakic patients in near gaze. The optic flexure may contribute to the near abilities of Crystalens patients and may help explain the excellent clinical results being achieved.Steven J. Dell, MD, is Director of Refractive and Corneal Surgery at Texan Eye Care in Austin. He is a consultant to Eyeonics, Inc., and Tracey Technologies, Inc. Dr. Dell may be reached at (512) 327-7000; email@example.com.
1. Dell SJ. Movement of the Crystalens IOL with pharmacological manipulation of accommodation. Paper presented at: The AAO/SOE Joint Meeting; October 22, 2004; New Orleans, LA.
2. Dick HB. Accommodative intraocular lenses: current status. Curr Opin Ophthalmol. 2005;16:8-26.
3. Waltz KL. Presbyopia treatment by IOLs. Paper presented at: The XXII Congress of the European Society of Cataract and Refractive Surgeons; September 19, 2004; Paris, France.